Electrocardiograms or arterial pressure signals have long been helpful in the treatment of patients when used in conjunction with intra-aortic balloon pumps. Japanese Patent Publication No. 62-189049 (1987) discloses one example of how arterial pressure signals can be obtained. As described in that publication, an arterial pressure sensor is set in place at the tip of the intra-aortic balloon pump.
However, when an arterial pressure sensor is set at the tip of the intra-aortic balloon pump, the intra-aortic balloon pump and the sensor are inserted completely into the patient's body. As a result, it is difficult to keep the pump properly calibrated by appropriately maintaining the zero point of the sensor. Therefore, with conventional devices, the zero point gradually fluctuates, thereby preventing users from accurately detecting arterial pressure. This is a problem that has been noted with conventional devices of the aforementioned type.
Other types of intra-aortic balloon pumps are disclosed in U.S. Pat. Nos. 4,692,148; 4,733,652; 4,794,910; 4,796,606; 4,809,681; and 4,832,005.